The demand valve is that part of the regulator that the diver holds in his mouth and which delivers the air to the diver as he inhales.
The casing of the demand valve at least partially contains the mechanism for regulating the pressure of and delivering the gas from the source via a supply hose. This pressure-regulating mechanism allows the gas carried by the hose to reach, selectively, an outlet intended to be connected to the diver's mouth (as a function of the external pressure and/or of the inhalation pressure). The systems providing the connection between a diver's demand valve and a fluidic connector (a hose, a valve seat retainer, etc.) generally comprise a system of the screw-nut type.
In certain known embodiments, the pressure-regulating valve part of the demand valve is housed in an insert arranged in a bore of the demand valve casing. That end of the insert that is situated in the casing also bears the lever of the pressure-regulating mechanism which collaborates with a flexible diaphragm situated on one side of the casing.
According to a first possible arrangement, the pressure-regulating valve seat is also housed in the insert. In such a case, the hose carrying the gas is then screwed directly onto the exterior end of the insert.
According to a second possible arrangement, the pressure-regulating valve seat is housed in a separate seat retainer which is coupled (for example by screw-fastening) to the exterior end of the insert. In such a case, the gas supply hose is then screwed not onto the insert but onto an end of the seat retainer.
Suitably robust screw-fastening and sealing are conventionally ensured by imposing a sufficiently high tightening torque. This tightening does, however, require suitable tightening tools (open-ended spanner, pin wrench, etc.) which are not necessarily available when needed. In addition, it is not easy for the user to identify that he has applied a sufficient tightening torque.
It is an object of the present invention to remedy all or some of the abovementioned disadvantages of the prior art.